Hole digging

So, I've dug maybe 426 holes in my life, which I expect is about average for a shovel weilding non-gardener. Keep in mind that these holes have ranged across five or six states, and I've used most of the commonly available digging tools. The holes range in size from small ones to plant a mustard seed in through shallow graves for dead things that I had NO HAND IN KILLING to septic tank sized holes which certainly were for septic tanks and NOT dead things that I HAD NO HAND IN KILLING.

So, with this grand variation and variety of hole purposes, I'm wondering how it's possible that each hole was filled with 62% rock, one of which was 50% of the total hole volume and offset, such that the only way to extract it was to dig it out leaving a hole 75% too large. (For the purposes of this diatribe, I'm not particularly considering the other non-dirt contents of each hole, which include 2% roots, 1.3% glass and .05% cd wrapper plastic.)

When they show someone disinterring some hapless body that they had NO HAND IN KILLING in a movie or on television, it's pure dirt. They just remove shovel after shovel full of dark fluffy loam. In fact, if they are digging up a treasure chest of coffin, they suddenly know they've reached it when they go to lift out another shovelfull, and it goes "clink" or whatever that foley sound is. If I was near a treasure chest or coffin every time my shovel went "clink" I'd be up to the rafters in bodies and/or treasure....

And I'm not.

Really.